Recovery of elastomeric material such as rubber from articles containing such material is increasingly popular due to the increasing costs of manufacture of the raw elastomeric material.
Used articles containing elastomeric material such as vehicle tires are currently not recycled but instead are discarded or dumped.
Such dumping poses a severe environmental problem and also results in the loss of a large amount of recoverable elastomeric material.
A significant source of recoverable elastomeric material comes from used vehicle tires, rubber conveyor belts or other such rubber containing products. Vehicle tires are normally discarded after a predetermined wear on the tread on the vehicle tire or upon damage of the vehicle tire however such used tires still contain a large amount of recoverable rubber.
Recovering elastomeric material from articles which consist entirely of such material can be carried out by cutting, shredding or grinding of the elastomeric material followed by recycling.
However, most articles containing elastomeric material also contain non-elastomeric material such as reinforcement and hitherto it has been difficult to recover the elastomeric material from the remaining portion of the article. For instance, vehicle tires are generally reinforced with textile chord and steel belts and hitherto it has been difficult to separate the desirable rubber from the reinforcement.
Earlier attempts to reclaim rubber from vehicle tires comprised the steps of grinding the vehicle tire to a small particle size followed by magnetic separation of the metallic reinforcement and screen separation of the non-metallic reinforcement (i.e. textile chord reinforcement). This process is cumbersome and expensive and results inefficient separation of the various components. Separation could be facilitated by softening the rubber before grinding by contacting the rubber with one or more solvents.
It has now been found that rubber and other elastomeric material can be more conveniently removed from articles by initially softening the rubber or elastomeric material on the article and then subjecting the article to shear conditions to remove the rubber of elastomeric material from the article. In this manner, grinding, magnetic separation and screen separation is not required.
It has further been found that the recovered elastomeric material can be carbonized by further radiation steps preferably using microwave radiation.